Looking for Schumacher INC-700A Schematic

[bob_2020]

Have this car charger, not working, not sure what is wrong with it. Display is not coming up.
I have poked around the board, have not found any glaring defects.

[sam_sam_sam]

Please post pictures of all of the boards front and back of the boards

[bob_2020]

Attached are pics of the front and back of circuit board.

[CapLeaker]

The top picture is not any good at all… just blurry. Do some better focused correctly, straight shot, higher resolution pictures.

[bob_2020]

Here is a better one.

[redwire]

I can see at least one fuse under the gluefest. Vertical F2 by D3 and the transformer. Check the fuse. If it's blown then we look for shorted out parts like Q4, Q3.
The glue is also cracked on some caps in the C29 cluster (by the current-sense shunts), which means they got prego and likely took the piss. Scrape off the glue and take a look.
The small black relay looks like for cap precharge so it should click once the DC bus comes up, if there is power on the primary side but I'm not optimistic.

[bob_2020]

Fuse is fine.
Relay does not click
Pulled those electrolytics, and checked esr and capacity and all good.

[redwire]

How many amps output is this rated? I imagine those 5 caps get stressed out and run hot.

I can't see a primary-side startup resistor, or a small transformer for a small aux switcher to make say 12V to power the primary IC. Somewhere this thing has a LV power supply for that- it must be under the heatsink then.
Can you post a pic of the backside of the heatsink, to see the parts there.

[redwire]

Second thing I always do with repairs is a visual inspection. With a magnifier and bright light, spend a couple minutes staring at it.
I forgot to mention I see some issues with the soldering on the PCB.

There's quite a few joints where the solder did not stick, like in the first pic.
Another joint looks like it was touched up but way too much heat was used. So the flux is burnt and likely the PCB trace and pad lifted off.
You can use a q-tip and IPA to gently clean off the old flux. I think the PCB is damaged there though.

[bob_2020]

70 amp output.
I included the pic under the heat sink.
I see 168v dc out from the rectifier.
I have reviewed the two issues you highlighted in the pics.
For the first pic, the solder joint is fine, it's just the lighting.
For the second pic, overheat issue, I cleaned up the spot and there is continuity between the joint and the trace.

[redwire]

OK, I see black carbon spit? out of the bridge rectifier D15 on the heatsink. But you measure 168VDC so it's working. Hmmm.
I think Q7 TS13005 provides a low voltage for the control IC to start up. I would expect low voltage on its emitter, something like whatever zener D24 is rated for, let's say 15VDC. (168V on the collector tab).
Be careful with this board, it's got massive primary caps 8,800uF total can bite if tghey have stray charge. The 220k's should discharge them slowly.

[bob_2020]

Yeah, when I saw the "black carbon spit" on the rectifier, I thought for sure it was a gonner.
For TS13005
G = 5.9v
D = 118v
S = 5.3v
D24
Anode = 0
Cathode = 4.6v

[redwire]

The bridge rectifier is surely damaged, or an arc from it to something else on the heatsink is what happened here. Of the 4 diodes in it, I can't see they all have survived.

For the primary side low voltage regulator, TS13005 NPN (BCE) the voltages look low... unless it's only a 5.3V rail? which is not enough really. It should be 12-15V at least, for the SMPS IC to start up. I can't make out its number A2494? You might have to carefully take voltage readings at each pin of the IC to see what it is doing. The TS13005 might be just overloaded a little and the voltage can't come up there. D24 should have higher voltage I would expect. What is the black relay's coil voltage written on it.

[bob_2020]

>The bridge rectifier is surely damaged,
Seems reasonable, though it is putting out 168v?

The relay is 12v written.

That chip is AZ494CP (on the back side of the large heatsink, right (see pic) ?)
Chip voltages:

1: 1.7	16: 1.7
2: 3.5	15: 3.4
3: 0	14: 3.6
4: .2	13: 3.6
5: 1	12: 4.7 (Vcc)
6: 2	11: 4.7
7: Gnd	10: 3.5
8 4.7	9: 0

[redwire]

The PWM IC AZ494 does not have enough supply voltage, it should be 12-15V on pin 12 V_CC and you measure only 4.7V, I think that power comes from the TS13005.

Hard to tell at this point if the rail is overloaded and has sagged down, or the startup regulator is just weak and can't supply enough. The pics need more light and less blurrrrrrr.

PWM output E1 Pin 9 I think should not be 0V, so I would look downstream at the gate driver to see if a transistor or power mosfet has shorted.
How does Q3 and Q4 (on the heatsink) look for GDS resistances? What is the little DIP-8 part number? It's got a delicate sensor going on top of it.

I have seen people use a 9V battery or external PSU to (only) power the SMPS IC to see what gets hot or smokes. No mains to the board though- just powering the IC ans looking to see if the SMPS section is drawing too much current or not.

I don't like the black spit out of the rectifier but for now the 168VDC is enough. It could have an open diode but that won't show up until there's load. TS13005 should be getting hot.

[bob_2020]

Well, I made this situation worse. I was checking if the TS13005 was getting hot. No, barely warm.
But, the board slipped and was on top of the cooling fan, which shorted something out, near where the mains come in. It made big sparky.

I don't know what damage that caused, quite for the night. Sorry, not sure if it is too far gone now. Arghhh...

How does Q3 and Q4 (on the heatsink) look for GDS resistances?.

For Q3 & Q4, I measured from Pint 1 (G) 3.2m ohms on Pin 2 (D) & 2.3m ohms Pin 3 (S).
55NM6OND
https://alltransistors.com/adv/pdfvi...d.pdf&dire=_st

What is the little DIP-8 part number? It's got a delicate sensor going on top of it

I am having trouble figuring out what this is.
The numbers on it are:
LG387E
KFB220

I have seen people use a 9V battery or external PSU to (only) power the SMPS IC to see what gets hot or smokes.

Nothing smoked or got hot/warm..